Display device, control method, and semiconductor device

Abstract

According to an aspect, a display device includes an image display panel and a driver driving the image display panel. The driver implements a first display mode in which a common voltage is a constant DC voltage; polarity of the video signal is inverted per a predetermined number of video signal lines; and the polarity of the video signal per a predetermined number of video signal lines is inverted in a frame unit, and a second display mode in which the common voltage is an AC voltage, polarity of which is inverted in a frame unit; the polarity of the video signal is opposite to the polarity of the common voltage; and the polarity of the video signal is inverted to be opposite to the polarity of the common voltage in a frame unit, and switches between these modes according to a mode switching signal from the outside.

What is claimed is: 
     
       1. A display device comprising:
 an image display panel including
 a plurality of pixels, 
 a plurality of scanning lines, each of which is coupled to the pixels arranged in a first direction, and to which a scanning signal is supplied, 
 a plurality of video signal lines, each of which is coupled to the pixels arranged in a second direction intersecting the first direction, and to which a video signal is supplied, and 
 a common electrode that is coupled to the pixels, and to which a common voltage is applied; and 
 
 a driver configured to drive the image display panel, wherein 
 the driver is configured to implement
 a first display mode in which the common voltage is a constant DC voltage; polarity of the video signal is inverted per a predetermined number of the video signal lines; and the polarity of the video signal per a predetermined number of the video signal lines is inverted in a frame unit, and 
 a second display mode in which the common voltage is an AC voltage, polarity of which is inverted in a frame unit; the polarity of the video signal is opposite to the polarity of the common voltage; and the polarity of the video signal is inverted to be opposite to the polarity of the common voltage in a frame unit, and 
 
 the driver is configured to switch between the first display mode and the second display mode in accordance with a mode switching signal supplied from the outside. 
 
     
     
       2. The display device according to  claim 1 , wherein
 the driver is supplied with a first voltage having positive polarity and a second voltage having negative polarity, 
 the driver includes
 a positive polarity boosting circuit configured to boost the first voltage and generate a third voltage, and 
 a negative polarity boosting circuit configured to boost the second voltage and generate a fourth voltage, 
 
 the driver is configured to cause the positive polarity boosting circuit and the negative polarity boosting circuit to operate in the first display mode to cause the third voltage to be a high potential side voltage of the scanning signal, and to cause the fourth voltage to be a low potential side voltage of the scanning signal, and 
 the driver is configured to cause the positive polarity boosting circuit and the negative polarity boosting circuit to stop in the second display mode to cause the first voltage to be the high potential side voltage of the scanning signal, and to cause the second voltage to be the low potential side voltage of the scanning signal. 
 
     
     
       3. The display device according to  claim 2 , wherein
 the driver further includes
 a positive polarity step-down circuit configured to step down the first voltage and generate a fifth voltage, and 
 a negative polarity step-down circuit configured to step down the second voltage and generate a sixth voltage, and 
 
 the driver is configured to switch between the fifth voltage and the sixth voltage in a frame unit in the second display mode to generate the common voltage. 
 
     
     
       4. The display device according to  claim 1 , wherein
 the driver further includes a DA converter configured to convert a binary input signal into a multi-gradation signal, 
 the driver is configured to cause the DA converter to operate in the first display mode to generate the video signal, and 
 the driver is configured to cause the DA converter to stop in the second display mode and cause the binary input signal to be inverted in accordance with the polarity of the common voltage to generate the video signal. 
 
     
     
       5. The display device according to  claim 1 , wherein the driver is configured to drive the image display panel in the second display mode at a frame rate lower than that in the first display mode. 
     
     
       6. The display device according to  claim 1 , wherein, in the second display mode, the driver is configured to cause a voltage difference between the common voltage in a case in which the common voltage has negative polarity and the video signal for obtaining maximum luminance to be different from a voltage difference between the common voltage in a case in which the common voltage has positive polarity and the video signal for obtaining the maximum luminance. 
     
     
       7. The display device according to  claim 1 , wherein an electric charge resetting period in which an electric charge of a pixel capacitor of each of the pixels is discharged in a frame unit is provided in the second display mode. 
     
     
       8. The display device according to  claim 7 , wherein the electric charge resetting period is provided in a vertical blanking period in which writing is not performed on the pixels before the polarity of the common voltage is inverted. 
     
     
       9. The display device according to  claim 7 , wherein image display is performed in any of a plurality of regions obtained by dividing a display region of the image display panel in a scanning direction in the second display mode. 
     
     
       10. The display device according to  claim 7 , wherein a writing period for performing writing on the pixels within one frame period in a region in which image display is performed is equal to or shorter than 10 [ms] in the second display mode. 
     
     
       11. A control method for controlling an image display panel, the image display panel including: a plurality of pixels; a plurality of scanning lines, each of which is coupled to the pixels arranged in a first direction, and to which a scanning signal is supplied; a plurality of video signal lines, each of which is coupled to the pixels arranged in a second direction intersecting the first direction, and to which a video signal is supplied; and a common electrode that is coupled to the pixels, and to which a common voltage is applied, the control method comprising:
 implementing a first display mode and a second display mode each having a different driving method for driving the image display panel; 
 in the first display mode, causing the common voltage to be a constant DC voltage, inverting polarity of the video signal per a predetermined number of the video signal lines, and inverting the polarity of the video signal per a predetermined number of the video signal lines in a frame unit; 
 in the second display mode, causing the common voltage to be an AC voltage, polarity of which is inverted in a frame unit, making the polarity of the video signal opposite to the polarity of the common voltage, and inverting the polarity of the video signal to be opposite to the polarity of the common voltage in a frame unit; 
 switching the second display mode to the first display mode in accordance with a first switching signal supplied from the outside; and 
 switching the first display mode to the second display mode in accordance with a second switching signal supplied from the outside. 
 
     
     
       12. A semiconductor device for driving an image display panel, the image display panel comprising:
 a plurality of pixels; 
 a plurality of scanning lines, each of which is coupled to the pixels arranged in a first direction, and to which a scanning signal is supplied; 
 a plurality of video signal lines, each of which is coupled to the pixels arranged in a second direction intersecting the first direction, and to which a video signal is supplied; and 
 a common electrode that is coupled to the pixels, and to which a common voltage is applied, wherein 
 the semiconductor device implements
 a first display mode in which the common voltage is a constant DC voltage; polarity of the video signal is inverted per a predetermined number of the video signal lines; and the polarity of the video signal per a predetermined number of the video signal lines is inverted in a frame unit, and 
 a second display mode in which the common voltage is an AC voltage, polarity of which is inverted in a frame unit; the polarity of the video signal is opposite to the polarity of the common voltage; and the polarity of the video signal is inverted to be opposite to the polarity of the common voltage in a frame unit, and 
 
 the first display mode and the second display mode can be switched in accordance with a mode switching signal from the outside.